In any large structure, whether it be a home or a large office building, it is desirable to have a centralized control system capable of controlling all the various electronic devices in the home or building. For example, in a multi-story office building, it is desirable for a building manager to be able to control the lights, fans, and other electronic devices on the various floors without having to physically go to each floor. One such way to implement this control system is to connect the various devices through either a wired or wireless network. Both of these solutions, however, have drawbacks. Wired networks can be time consuming and costly to implement, and wireless networks frequently have poor signal quality and even dead zones throughout a building.
A cost effective means for networking devices is to use the existing power line infrastructure within a borne or building, making it possible for one device to communicate with another without the expense of rewiring. Power line communication, however, also presents many challenges, the biggest of which is noise. Power lines contain strong impulsive noise as well as other types of noise caused by the specific devices connected to the power lines. Every device is going to create unique noise, and in the case of some devices, such as an elevator, that noise can be exceptionally strong.
Another challenge in transmitting data across power lines is developing a system that can operate in a multitude of environments. For example, in a building the lighting may operate at 277 volts while devices plugged into the all outlets operate at 110 volts. Voltages, as well as frequency regulations, can also vary from country to country. Another challenge in using the power lines as a communications medium is the low external impedance of the power lines, making it difficult to couple a transceiver to the power lines. Adding to the challenge is the fact that all environments are different. The noise, impedance, and voltage levels will change from country to country, building to building, and even room to room within a building.
In light of the foregoing challenges, a new system for reliably transmitting data over power lines is desirable.